It's been 60 years since Walt Disney first opened the gates to Disneyland, and the happiest place on earth is celebrating its anniversary with a big party airing Sunday night.

The members of Pentatonix put their own special spin on the song "Be our Guest" from "Beauty and the Beast" in "The Wonderful World of Disney: Disneyland 60" anniversary party.

"It means a lot for us to be a part of the show," said Scott Hoying of the group. "We grew up on Disney music, and now we're here. It's super cool."

There are plenty of long-time Disney fans packing the two-hour celebration.

"I love Disneyland. If I don't go at least once a year, which sounds very extravagant, but if I don't go once a year, I start to have some sort of weird withdrawal," said "Scandal" actress Kerry Washington.

Former Disney Channel star Hilary Duff also showed enthusiasm for the celebration.

"I think I was about four my first time going to Disneyland, and we drove from Texas to California, and we made our parents ride 'It's a Small World' over and over and over and over again," she said.

Another proud member of the Disneyland fan club: Dame Helen Mirren. She recalled her first time going to the park as an unforgettable day with her family.

"It was, just, absolutely magical. So when my mom came to visit, the one place I wanted to take her to was Disneyland," she said. "And I'll never forget as we left, you know, she was saying, 'There was a sign up saying Disneyland is magic,' She said, 'Yes, that's true.'"

"The Wonderful World of Disney: Disneyland 60" begins at 8 p.m. Sunday on ABC.